Mechanism for forming prongs or barbs in sheet metal strips



1. s. REID 3,094,158 MECHANISM FOR FORMING PEoNGs 0R BARBs 1N SHEETMETAL STRIPS 5 Sheets-Sheet l June 18, 1963 Filed June 27, 1960INVENToR. rv/156 Havo grr-ORNE YS 3 Sheets-Sheet 2 J. S. REID MECHANISMFOR FORMING PRONGS OR BARBS IN SHEET METAL STRIPS June 18, 1963 FiledJune 2'?, 1960 June 18, 1963 REID 3,094,158

J. S. MECHANISM FOR FORMING PRONGS OR BARBS IN SHEET METAL STRIPS FiledJune 2'?, 1960 5 Sheets-Sheet 3 INVENTOR. fsf/vas o. Revo Ohio Filed.lune 27, 1960, Ser. No. 38,920 6 Claims. (Cl. 153-2) 'Ihis inventionrelates to apparatus for forming attaching prongs or barbs in sheetmetal strip material such as core material in trim structures, sealingstructures and the A like. 'I'he prongs or barbs are formed while thestrip material is fiat, prior to its being bent into channel shape, andthe present invention relates, in particular, to a punch and die -setadapted for sequentially lforming the barbs in successive lengths of theilat strip as it is indexed through the apparatus.

ln the form of the invention as herein illustrated and described, thesheet metal strip in which the prongs or barbs are formed is constructedby arranging a narrow band or ribbon of sheet metal in partiallyoverlapping folds which are angularly inclined relative to each other tin generally zigzag form and wherein the prongs or barbs are located inthe overlapping end portions of the zigzag band. This type of stripstructure has the particular advantage that it remains completelyflexible when bent into channel-like configuration or other similar formpreparatory to its being used as core material. Said core stripstructure which has been thus formed with, for example, the barbs bentinwardly toward the center of the channel, may be covered with cloth orother resilient sealing material and utilized as a trim strip, sealingstrip, or the like whereby said channel-like structure may be placedover an exposed, sheet metal edge such that the inwardly projectingbarbs grip or bite into opposed surfaces of the sheet metal 4adjoiningsaid edge, th-us preventing removal of the strip structure, whileenabling said sealing material to overlie said edge.

It will be understood that the above is given merely by way of exampleindicating one particular utility of the strip structure as thus formedby the apparatus of the present invention and is not intended to limitthe scope thereof.

It is therefore an object of the present invention to prov-ide apparatus`especially `designed for forming a plu- Vrality of barbs or projectionsalong a predetermined length of strip material.

Another object of this invention is to provide novel and improvedforming apparatus which is especially designed for fabricating a seriesof barbs or projections adjacent the longitudinal edges of stripmaterial.

Still another object of the present invention is to provide in anapparatus of the above type means for automaticallyv removing the stripmaterial from the forming apparatus after the projections or barbs havebeen formed therein.

A further object is to provide strip forming apparatus which includesmeans for automatically disengaging the projection forming means fromthe strip material after saidbarbs are formed therein.

Other objects and advantages of this invention and the invention itselfwill be understood from the following specification and the accompanyingdrawings, and in which said drawings:

FIG. l is a front elevationof forming apparatus embodying the presentinvention;

FIG. 2 is a top plan view;

FIG. 3 is an end elevation; l

s FIG. 4 is a view similar to FIG. 3 and showing the forming apparatusin its closed or forming position;

VUnited States Patent O M 3,094,158 VPatented June 18, 1963 lCe 2 FIG. 5is a longitudinal section taken along the line 5-5 of FIG. 3;

FIG. 6 is an enlarged detail plan view of the punchreceiving grooves inthe die part of the forming apparatus of the present invention;

FIG. 7 is a side elevation of one barb forming tool of the instantapparatus;

FIG. 8 is a front elevation of the tool of FIG. 7;

FIG. 9 is a section taken along the line 9-9 of FIG. 7; FIG. l0 is atransverse detail section taken through the forming apparatus in itsclosed position as shown in FIG. 4, and,

FIG, lvl is a plan v-iew of one type of core strip material for whichthe forming apparatus of the present invention is especially designed.

Referring now to the drawings in all of which like parts are designatedby =like reference characters, the `forming apparatus of this inventionis herein disclosed in an embodiment of a punch and die generallyindicated by the reference numerals 1 and 2, respectively. The die 2 isadapted to -be rigidly secured to a base 1i` of a punch press in anysuitable manner such as by means of bolts 4. The punch 1 is similarlysecured in any suitable manner to a vertically reciprocable head 5 ofthe press. Strip material indicated at 6 is indexed through the punchand die of this invention by suitable indexing means (not shown) 1whereby a uniform, predetermined length of said strip material ispresented above the die 2 for each downward movement of the punch 1.

Referring now particularly to FIGS. l, 3, and 5, the punch 1 comprises apair of elongated, rectangular retainer blocks 10 each rigidly anduniformly mounting a plurality of `downwardly directed punching orpiercing tools 11. The tools 11 are telescopically interftted into aplurality of longitudinally evenly interspaced, vertical apertures 12 inthe retainer blocks 10. The punches 11 are positioned in straight rowsthrough the medial portions of the retainer block 10, and said retainerblocks are secured together by bolts 23 with Ione of the 'longer lateralsides of each said block being in atwise contact Y with a similar sideof the other block.

As best seen in lFIGS. 3 and 4 each punching tool 11 is -held securelywithin its respective aperture 12 by means of a horizontally directedset screw 13' which is thread tted into the respective retainer blockfrom the inner surface of said block. Each retainer block 10 is alsostepped outwardly adjacent its lower surface as indicated at 14, thestepped portions 14 being complementary to form a downwardly open andlongitudinally continuous inverted channel inthe pair of contiguousblocks, said channel being' indicated at 15. Adjacent the lowermost edgeof each of the steps 14 there is provided an inwardly directed lip ortrack -16` which is continuous throughout the length of each retainerblock.

`-rpair of complementary sockets which are formed by matching,semi-circular, concave grooves 20 in the retainer blocks 10.Intermediate the guide pins 19, the

stripper block is provided with a plurality of upwardly open, preferablycylindrical sockets 21 adapted to seal telescopically intertting coilsprings 22. 'The coil springs t 22 are compressed between the sockets 21and the matching retainer blocks 10 within the recess 15 whereby thestripper block 17 is resiliently and retractively biased downwardly withthe shoulders 18 resting upon the lips 16 to limit the downward movementof said stripper block. The stripper block 17 is normally biaseddownwardly to a position whereby the lowermost surface of said stripperblock is below the lower ends of the punching tools 11, said stripperblock having sufficient vertical mobility whereby it can be retractedupwardly to a position slightly above the lower tips of the punchingtools, as best seen in FIGS. 4 and ll0.

Referring now particularly to FIGS. 7-9, each punching tool 1-1preferably comprises an elongated shank 30 lhaving a attened :area 31spaced downwardly a short distance from the upper end thereof andpositioned on the front side of said tool, said flattened area adaptedto coact with one of the said screws 13 to retain said tool within itsrespective retainer block and to prevent rotation of the same.

The lowermost end or piercing portion 32 of the tool is preferablytriangular in section with the apex of the triangle being directedtoward the front of the tool. The rear surface of the piercing portion32 tapers downwardly toward the front or apex of the triangle asindicated at 33 in FIG. 7. The lowermost tip 34 of said piercing portionis flattened slightly, and the rear surface 33 intersects a horizontalshoulder 35 in an upward direction. The resulting structure comprises atool having a very small, triangular piercing tip 34 which rstpenetrates the metal, said metal being sliced or cut by continueddownward movement of the tool to form a downwardly angled, sharptriangular barb in the strip material 6.

As best seen in FIGS. 1, 2 and 5, the die 2 comprises yan elongated dieblock 40 which .is substantially narrower in its transverse dimensionthan the combined width of the contiguous container blocks 10 and 4isprovided at the ends thereof with -longitudinally extending, downwardlystepped, integral mounting blocks 41. The blocks 41 are suitablyapertured at 41a to receive the bolts 4 by which the die block 40 issecured to the base or bed 3 of the press. The sides of the die blocks-are recessed inwardly as indicated at 42 in the longitudinal medialregion of the die blocks, said recess extending from the bottom edge ofthe die blocks upwardly approximately 1/2 of the vertical dimension ofthe die blocks.

Above the recess `42 on each lateral side, said die block is providedwith vertically disposed V-shaped grooves 43 corresponding with thenumber of downwardly directed punching tools 11. The tools 11, as shownin FIGS. 3, 4 and 10, are all positioned with the apexes of the piercingportions 32 facing inwardly in such manner that the tools will interiitthe V-shaped groove 43. In the form of the invention as hereinillustrated, the grooves 43 and the corresponding punching tools 1.1 arelongitudinally staggered in their spacing to correspond with the zigzagtype of strip material 6 being formed.

The die block 40 is provided with a longitudinal channel 44 in its uppersurface adapted to slidably receive a clearance block 45. The clearanceblock 45 is vertically aligned with the stripper block 17 and ispreferably of substantially the same -transverse dimension. Saidclearance block has downwardly directed guide pins 46 which slidablyinterlit complementary apertures 47 in the guide block 40. Intermediatethe guide pins 46, said guide block is provided with a plurality ofupwardly open sockets 48 providing seating means for compression springs49 which project upwardly above the bottom of the channel 44 andnormally maintain the clearance block 45 in the elevated position asshown in FIGS. 3 and 5.

Side plates 50 are contiguously secured in fiatwise engagement againstthe lateral or grooved sides of the die block 40 by means of bolts 51.Said side plates are of the same vertical dimension as the die block 40and of such length as to iit longitudinally between the mounting blocks41 which overlap the ends of said side plates.

The strip material 6 herein illustrated comprises a narrow band of sheetmetal in generally zigzag form such as that attained by Winding `saidband iuto a continuous series of helical loops and subsequently atteningthe same. The resulting strip material comprises a series oflongitudinally interspaced, overlapping end portions 60 of doublethickness. The barbs which are formed by the punch and die set of thisinvention and which are indicated at 61 (FIG. l0) have unusual strengthand effectiveness due to the double thickness of the metal in thepresent instance. Strip of this type has the particular advantage thatit can be transversely formed in any desired contiguration withoutlosing its inherent strength and flexibility.

As the strip material 6 is indexed through the punch `and die set, itrests upon and is supported by the clearance block 45 which maintainsthe strip in vertically spaced relationship with the upper surface ofthe `die block 40 whereby newly formed barbs or prongs 61 are clear ofthe V-shaped grooves 43. With the punch and die in the open position,the strip is indexed longitudinally a distance equal to that covered bythe punching tools 11 'and their respective grooves 43. At this time,the stripper block 17 is in its lowermost position Ias shown in FIG. 3somewhat below the punching tools 11.

After the strip 6 has been moved along the correct distance, the punch 1closes downwardly upon the die 2 to perform the forming operation. Thestripper block 17 first contacts the upper surface of the strip material6 whereby said material is firmly held by the resilient pressuresexerted upon it by said stripper block and the clearance block 45. Thisinsures that the strip will remain in the proper position while it isbeing punched.

As the punch 1 continues downwardly, the clearance block 45 retractsi-nto the die block 40 and the strip 6 is pressed downwardly against theupper surface of the die block 40 and the upper edge surfaces of theside plates 50. The stripper block 17 concurrently retracts upwardlyallowing the punching tools 11 to project downwardly below said stripperblock, to pierce the strip 6, :and enter the grooves 43. As wellillustrated in FIG. 10, the piercing portions 32 of the tools 11penetrate the end portions 60 of the strip material only suiciently toform the barb 61 without cutting laterally through to the edges of saidend portions.

As the punch 1 retracts upwardly on its return stroke, the strip 6 issimultaneously disengaged from both the punching tools 11 and thegrooves 43 of the die block 40. The clearance block 45 immediatelyelevates the strip 6 upwardly to pull the barbs 61 out of the grooves43, and the downward pressure of the stripper block 17 effectivelyremoves said strip from the piercing portions 32 of the punching tools.Because the barbs 61 are formed in straight rows in laterally spacedrelationship to the clearance block I45, there is, of course, nointerference between said barbs and said clearance block.

As a result of the construction as herein disclosed, strip material maybe rapidly and eflciently indexed through 1a punch press machine to formprongs or barbs adjacent the edges of strip material withoutinterference of the newly `formed barbs with either the punch or thedie. The triangular shape of the lbarbs as formed has been found toprovide optimum holding power in installations for which strip materialof this type is adapted.

It will be understood that many departures from the details of thisinvention as herein disclosed and illustrated may be made without,however, departing from the spirit thereof or the scope of the appendedclaims.

What is claimed is:

1. In forming apparatus for forming barbs in deformable strip material,a die block having a pair of parallel rows of punch receiving grooves inparallel sides thereof and retractable support means disposed betweensaid rows of grooves `and normally projecting upwardly above said dieblock and supporting said strip material.

2. Apparatus for forming barbs in deformable strip material comprising adie block having rows of punch receiving grooves in parallel sidesthereof, retractable support means projecting upwardly from said dieblock between said rows of grooves to support said strip material, and apunch having penetrating means adapted to depress said strip intocontact with said die block and coact with said openings to form barbsin said strip.

3. A device for forming barbs in deformable strip material comprising adie and a complementary punch, means for bringing said punch and dieinto operating relationship in a sequence of repeated formingoperations, said die comprising a die block having two rows of evenlyspaced, vertical grooves in parallel sides of said lblock, said punchcomprising retainer means having parallel rows of downwardly directedpunching tools adapted to pass downwardly and enter said grooves, aresiliently retractable stripper block mounted in said punch betweensaid rows of tools ,and normally projecting downwardly therefrom belowsaid punching tools, a resiliently retractable clear- Iance blockmounted in said die -block `between said rows of grooves and projectingupwardly 'above said die block, said clearance block adapted to supportstrip material threaded through said die beneath said punch, said toolsbeing formed `complementarily to said grooves whereby in each formingoperation they force said strip downwardly upon said die block andpenetrate said strip to form downwardly projecting barbs therein, saidstripper rblock retracting upwardly above the lower ends of saidpunching tools during each for-ming operation, said stripper lblockextending downwardly when said punch moves away from said die to removesaid strip material from said punching tools and said clearance blockconcurrently returning to its upwardly biased position and disposingsaid barbs above said grooves.

4. An apparatus -for continuously forming barbs in deformable stripmaterial as the material is indexed through said apparatus, saidapparatus comprising an elongated rectangular die block having vertical,V-shaped grooves in lateral sides thereof, a pair of side platescontiguously positioned against said lateral sides, said die blockhaving a longitudinally centrally disposed channel therein, a clearanceblock 4for supporting strip material disposed within said channel havingdownwardly directed guide pins slidably disposed within sockets locatedin the bottom of said recess, spring means normally biasing saidclearance block upwardly above the upper surface of said die block, apunch comprising retainer means having tools adapted to be projecteddownwardly into said grooves in a forming operation, said retainer meanshaving a longitudinally centrally disposed, inverted channel, a stripperblock disposed within said inverted channel having upwardly directedguide pins slidably disposed within sockets located in said retainermeans, spring means normally biasing said stripper block in a downwarddirection, means associated with said stripper block and said retainermeans limiting the downward movement of said stripper block, said punchmovable in a sequence of forming operations coordinated with theindexing of strip material through said apparatus, said clearance blockand said stripper block retracting when said punch comes into operatingrelation to said die whereby said cutting tools penetrate said stripwhile said strip is held between said stripper block and said clearanceblock, and upon movement of said punch upwardly, said material isstripped from said punching tools by said stripper block as it returnsto a downward position, and said strip material is lifted to an elevatedposition above said die block by said clearance block in which positionsaid strip is moved longitudinally through said die a predeterminedamount.

5. A device for forming barbs in deformable strip material comprising adie and a complementary punch, means Ifor bringing said punch and dieinto operating relationship in a sequence of repeated formingoperations, said die comprising a die block having vertical grooves inparallel sides of said block, said punch comprising retainer meanshaving downwardly directed punching tools adapted to pass downwardly andenter said grooves, a resiliently retractable clearance block mounted insaid die block between said rows of grooves and projecting upwardlyabove said die block, said clearance block adapted to support stripmaterial threaded through said die beneath said punch, said tools beingformed complementarily to said grooves whereby in each forming operationthey force said strip downwardly upon said die block against the upwardbias of said clearance block and penetrate said strip to form downwardlyprojecting barbs therein, said clearance block returning to its upwardlybiased position after each forming operation and disposing said barbsabove said grooves.

6. An apparatus for continuously forming barbs in deormable stripmaterial as the material is indexed through said appa-ratus, saidapparatus comprising an elongated rectangular die block having verticalgrooves in lateral sides thereof, a pair of side plates contiguouslypositioned against said lateral sides, said die block having alongitudinally centrally disposed channel therein, a clearance block forsupporting strip material disposed within said channel having downwardlydirected guide pins slidably disposed within sockets located in thebottom of said recess, spring means normally biasing said clearanceblock upwardly above the upper surface of said die block, a punchcomprising retainer means having tools adapted to be projecteddownwardly into said grooves in a forming operation, said punch movabledownwardly in a sequence of forming operations coordinated with theindexing of strip material through said apparatus, said clearance blockretracting when said punch comes into operating relation to said diewhereby said cutting tools penetrate said strip and upon movement ofsaid punch upwardly, said strip material is lifted to an elevatedposition above said die block by said clearance block i-n which positionsaid strip is moved longitudinally through said die a pre* determinedamount with the newly formed barbs passing on either side of saidclearance block.

References Cited in the tile of this patent UNITED STATES PATENTS1,468,271 Bechtel Sept. 18, 192-3 1,925,034 Fitzgerald Aug. 29, 19331,931,420 Wakeeld Oct. 17, 1933 2,003,448 Kruse June 4, l1935 2,800,960Cutler July 30, 11957 2,834,096 Norton May 13, 1958

1. IN FORMING APPARATUS FOR FORMING BARBS IN DEFORMABLE STRIP MATERIAL,A DIE BLOCK HAVING A PAIR OF PARALLEL ROWS OF PUNCH RECEIVING GROOVES INPARALLEL SIDES THEREOF AND RETRACTABLE SUPPORT MEANS DISPOSED BETWEENSAID ROWS OF GROOVES AND NORMALLY PROJECTING UPWARDLY ABOVE SAID DIEBLOCK AND SUPPORTING SAID STRIP MATERIAL.